1. Field of Invention
The present invention relates to a drained water recovery system and operating method thereof. More particularly, the present invention relates to a drained water recovery system of a process device and an associated recovering method.
2. Description of Related Art
In the fabrication of integrated circuit devices, one of the most frequently performed processes is wafer cleaning. In a wafer cleaning process, organic compounds, metallic impurities and micro-particles are removed from the surface of a wafer. However, most wafer cleaning processes need to consume large quantities of water. In fact, a large portion of the production cost for fabricating the integrated circuits lies in the purchase of pure water. Hence, pure water, cooling water for processing or cooling water for cooling towers is often recycled. If the process of recovering drained water for reuse is properly done, expenses on the necessary water resources and hence production cost can be reduced to boost market competition.
However, if the recovery targets at water quantity instead of water quality, the usage of the recovered water may be limited and the ultra-pure water may be contaminated leading to a drop in productivity. In many cases, the loss in yield that results from the use of contaminated water can hardly warrant the increase in the quantity of recovered water. Therefore, an efficiently managed water recovery system is very important.
The drained water recovery system of a process device operates in most semiconductor plants by collecting different types of drained water into a central location before sorting out into usage categories according to water quality. Although this method of recovering drained water is able to increase the quantity of recovered water, the quality of the recovered water cannot be improved. This type of recovery system often leads to some restrictions on the servicing capacity of the recovered water. Moreover, if a particular type of process drained water is problematic, the entire collection of drained water may have to be discarded.